CAUSE
The MAPI address space in PGP Desktop has to be configured to allow specific FAX address spaces.
SOLUTION
Add the following values to PGPprefs.xml<key>MAPIfaxAddressSpaceList</key>
<string>FAX</string>
-To find PGPprefs.xml, go to \%username%\UPM_Profile\AppData\Roaming\PGP Corporation\PGP \PGPprefs.xml
-Edit PGPprefs.xml in notepad.
-Find <key>MAPIfaxAddressSpaceList</key>
-Look next text to this string, it will show as <string></string>.
-Replace to <string></string> as <string>FAX</string>,
Note: Same will be performed in entire PGPprefs.xml file wherever you get <key>MAPIfaxAddressSpaceList</key>
-Once it will replace, text will be shown as below.
<key>MAPIfaxAddressSpaceList</key> <string>FAX</string>,
-Log off and relogin back to PC, and check fax services. It should work.